In recent years, rigid foam panelling has been used increasingly in the building trade, and various machines for forming the panelling and mixing the foaming chemicals are known. When depositing foam in an open top trough or mold, no particular difficulties arise with respect to the size of the mixing and depositing unit. However, when rigid outer skins are to be assembled with the foam as a core, there are considerable problems in the prior art.
When the rigid outer skins are assembled and substantially in their final position, that is parallel to each other and spaced a small distance apart before the foaming chemicals are deposited between them, long thin probes have been used to conduct the mixed chemicals into the space between the outer skins and deposit the chemicals. Such a probe is required to be as long as the panels are wide, which may be 3 to 6 feet, for example. It is desirable to have the chemicals foam as quickly as possible after the assembly moves into the curing and pressure tunnel of a conventional system, but quickly foaming chemicals present numerous problems in a long probe. Further, there is the difficulty of cleaning such a long probe.
It has been known to connect panels together at their edges opposite from the foam depositing means and pivot them apart a relatively great distance to insert the conventional bulky foam mixing units into the thus formed space, but this is very difficult with rigid outer skins, such as ribbed sheet steel, and in fact impossible when the sheet steel is provided in continuous strips, from for example a rolling mill, without having an excessive distance between the foam depositing station and the pressure tunnel to allow the sheet steel to be twisted to a parallel condition; such a long transition run would require that the foam chemicals have considerable delay in their foaming, which would in turn undesirably greatly lengthen the curing tunnel.